Tête nucléaire (French nuclear warhead serial).

Thermonuclear.

Transposon when immediately followed by a number.

Telephone number

Trigeminal neuralgia.

Women commonly use the term "TN" to refer to Tampons

The TN visa, a type of work visa for citizens of NAFTA countries working in the United States

Thursday Next.

Air Tahiti Nui (IATA airline designator).

Tamil Nadu (Indian state).

Tennessee (United States postal abbreviations).

Texas and Northern Railway (AAR reporting marks TN).

Tunisia (ISO 3166-1 alpha-2 country code).

Twisted Nematic, a technology used in TFT LCD computer displays.

True Neutral, an alignment in the role-playing game Dungeons & Dragons.

The TN postcode area named after Tonbridge, England.

ISO 3166-2:IT code for the province of Trento in Italy.